The invention relates to the field of connecting springs used in blocks known as junction blocks.
It is known practice, in order to make an electrical connection between the conducting end of an electric cable and an interconnecting part placed inside the junction block, to employ a connecting spring intended to keep the conducting end of the electric cable in contact with a conducting element in an electrical relationship with the interconnecting part.
Known junction block connecting springs generally form a kind of loop. As a preference, such connecting springs are made by bending a strip of conducting material. A spring according to the prior art comprises a branch known as the pressing branch intended, as often as not, to be in contact with a tab of the interconnecting part of the junction block. The spring further comprises a manipulating branch and an elastic bow connecting the pressing branch to the manipulating branch. The spring finally comprises a moving connecting branch extending the manipulating branch on the opposite side to the elastic bow and having means of connection for at least one electric cable and, more specifically, for the conducting end thereof. The connecting means are, as often as not, produced in the form of an opening intended to accommodate the conducting end of the cable.
A spring such as this is used by placing the pressing branch against the interconnecting part so that the connecting opening of the moving branch is, in the position of rest, retracted with respect to a passage through which the electric cable is introduced into the block which also has a passage for a tool designed to act on the manipulating branch of the spring.
Thus, when there is a desire to connect an electric cable, the end thereof is introduced into the passage of the block and the operator exerts pressure on the manipulating branch so as to move the latter closer to the pressing branch so as to bring the connecting opening to face the passage and thus allow the conducting end of the cable to pass into the opening. The operator then releases his action on the manipulating branch and the elastic bow then returns the manipulating branch and the connecting branch, which is connected to it, to the position of rest to press the conducting end of the cable against a conducting element.
Such springs are generally satisfactory in terms of their connecting function but nonetheless have the disadvantage of offering a structure which does not allow high elastic return forces to be obtained unless the dimensions of the spring, and therefore its size, are increased. Now, increasing the dimensions of the spring is an obstacle to the desired reduction in the size of the junction blocks that employ such springs.
The invention therefore sets out to overcome this drawback by proposing a new connecting spring which, for an equivalent bulk, makes it possible to obtain return forces which are higher than those of the springs according to the prior art.
Thus, the new spring, according to the invention, advantageously makes it possible to obtain either, for the same bulk, a spring which offers a higher return force or, for a given return force, a spring of smaller bulk.
In order to achieve this objective, the invention is aimed at a connecting spring for a junction block of the type forming a kind of loop and comprising:
a pressing branch,
a manipulating branch,
an elastic bow connecting the pressing branch to the manipulating branch, and
a moving connecting branch extending the manipulating branch on the opposite side to the elastic bow and having connecting means for at least one electric cable.
According to the invention, the connecting spring is one which further comprises a return branch which is connected to the pressing branch at the opposite end to the elastic bow by an elastic elbow and which is intended to collaborate with the manipulating branch.
According to another feature of the invention, the return branch has, on the opposite side to the elastic elbow, a pressing heel intended to collaborate with the manipulating branch. This advantageous arrangement of the invention makes it possible to make it easier for the end of the return branch to slide over the manipulating branch as the spring contracts.
According to another feature of the invention, when the spring is in the position of rest, the return branch is in contact with the manipulating branch.
According to yet another feature, the elastic elbow connecting the return branch to the pressing branch is preloaded.
According to yet another feature of the invention, the return branch and the elastic elbow define a stop that limits the extent to which the pressing branch and the manipulating branch can move closer together.
According to yet another feature of the invention aimed at reducing the bulk of the connecting spring, at least part of the elastic bow connecting the pressing branch to the manipulating branch lies, with respect to the plane defined by the pressing branch, on the opposite side to the manipulating branch.